Referência geoquímica regional para a interpretação das concentrações de elementos químicos nos sedimentos da bacia do Lago Paranoá - DF

The present study aimed at determining a regional geochemical reference for sediment samples from Lago Paranoá watershed through the formulation of geoaccumulation indexes. The need for obtaining information from areas representing low human impact was the basis of this work. Systematic evaluations of sediment from Lago Paranoá will bring valuable information regarding the potential risk that this layer represents for aquatic organisms. Thus, despite the recent water quality improvements achieved in this ecosystem, contaminants incorporated in the sediments may be remobilized for alterations in the adjacent environment. The adsorption capacity of chemical elements in sediment samples was controlled through the variation in the amounts of organic matter, the mineralogical composition and the granulometric variation. By creating the Sediment Enrichment Index (SEI) through the normalization of analytical data it was possible to establish the magnitude of this enrichment relatively to naturally occurring concentrations all over the region of interest. Normalized values with organic matter were especially useful for the evaluation of lothic systems.

Toxic Metal Distribution in the Core Sediment of Cochin Estuarine System (CES)

This article present the result from a study of two sediment cores collected from the environmentally distinct zones of CES. Accumulation status of five toxic metals: Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu) and Lead (Pb) were analyzed. Besides texture and CHNS were determined to understand the composition of the sediment. Enrichment Factor (EF) and Anthropogenic Factor (AF) were used to differentiate the typical metal sources. Metal enrichment in the cores revealed heavy load at the northern (NS1 ) region compared with the southern zone (SS1). Elevation of metal content in core NS1 showed the industrial input. Statistical analyses were employed to understand the origin of metals in the sediment samples. Principal Component Analysis (PCA) distinguishes the two zones with different metal accumulation capacity: highest at NS1 and lowest at SS1. Correlation analysis revealed positive significant relation only in core NS1, adhering to the exposition of the intensified industrial pollution

Amino acid data of catchment and sediment core samples of four Indian lakes

In the present study, we report the results of comprehensive amino acid (AA) analyses of four Indian lakes from different climate regimes. We focus on the investigation of sediment cores retrieved from the lakes but data of modern sediment as well as vascular plant, soil, and suspended particulate matter samples from individual lakes are also presented. Commonly used degradation and organic matter source indices are tested for their applicability to the lake sediments, and we discuss potential reasons for possible limitations. A principal component analysis including the monomeric AA composition of organic matter of all analysed samples indicates that differences in organic matter sources and the environmental properties of the individual lakes are responsible for the major variability in monomeric AA distribution of the different samples. However, the PCA also gives a factor that most probably separates the samples according to their state of organic matter degradation. Using the factor loadings of the individual AA monomers, we calculate a lake sediment degradation index (LI) that might be applicable to other palaeo-lake investigations.

Shallow water marine sediment bacterial community shifts along a natural CO2 gradient in the Mediterranean Sea Off vulcano, Italy

The effects of increasing atmospheric CO(2) on ocean ecosystems are a major environmental concern, as rapid shoaling of the carbonate saturation horizon is exposing vast areas of marine sediments to corrosive waters worldwide. Natural CO(2) gradients off Vulcano, Italy, have revealed profound ecosystem changes along rocky shore habitats as carbonate saturation levels decrease, but no investigations have yet been made of the sedimentary habitat. Here, we sampled the upper 2 cm of volcanic sand in three zones, ambient (median pCO(2) 419 µatm, minimum Omega (arag) 3.77), moderately CO(2)-enriched (median pCO(2) 592 µatm, minimum Omega (arag) 2.96), and highly CO(2)-enriched (median pCO(2) 1611 µatm, minimum Omega (arag) 0.35). We tested the hypothesis that increasing levels of seawater pCO(2) would cause significant shifts in sediment bacterial community composition, as shown recently in epilithic biofilms at the study site. In this study, 454 pyrosequencing of the V1 to V3 region of the 16S rRNA gene revealed a shift in community composition with increasing pCO(2). The relative abundances of most of the dominant genera were unaffected by the pCO(2) gradient, although there were significant differences for some 5 % of the genera present (viz. Georgenia, Lutibacter, Photobacterium, Acinetobacter, and Paenibacillus), and Shannon Diversity was greatest in sediments subject to long-term acidification (>100 years). Overall, this supports the view that globally increased ocean pCO(2) will be associated with changes in sediment bacterial community composition but that most of these organisms are resilient. However, further work is required to assess whether these results apply to other types of coastal sediments and whether the changes in relative abundance of bacterial taxa that we observed can significantly alter the biogeochemical functions of marine sediments.